Conversion means, "To turn back morally, to reform: Mt. xiii. 15; Mk. iv. 12; Lk. xxii. 32; Acts iii. 19; xxviii. 27" (Thayer's Greek-English Lexicon, pp. 243–244). According to W.E. Vine, "The word implies 'a turning from and a turning to…'" (Vine's Expository Dictionary).
Having embraced the teachings of John Calvin, most of the denominational world believes that conversion is a miraculous change brought about by the operation of the Holy Spirit.
According to Calvinists, an individual's salvation lies entirely at the discretion of God. They believe that nothing a person does can effect his salvation because no unregenerate person can do good -- his every act is sinful. They believe God must take direct, miraculous action to save a person's soul.
Matthew 13:15 is a refutation of this erroneous view. It states, "For this people's heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed; lest at any time they should see with their eyes, and hear with their ears, and should understand with their heart, and should be converted, and I should heal them." It is immediately apparent from this passage that the change Jesus was stressing comes about as a result of hearing, seeing and understanding the will of God.
Matthew 18:3 makes it clear that conversion is a responsibility enjoined upon man, not an act performed on him. "Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven." Jesus was showing His disciples what they needed to do, or whom they needed to become like, in order to be greatest in the kingdom of heaven (see v. 4). He was not showing what God does for men to make them great in the kingdom.
Acts 3:19 says, "Repent ye therefore, and be converted, that your sins may be blotted out..." Because remission of sins is the blessing promised in this verse and in Acts 2:38, it would seem reasonable that the apostle Peter would give the same instructions. In Acts 2:38 he said, "to repent and be baptized" and in Acts 3:19 he commanded people, "to repent and be converted." While repentance is common to both verses, the other requirement appears to vary until one realizes that baptism is involved in bringing about the conversion of a person (cf. Rom. 6:3–4, 17).
The free agency of man. Conversion requires the free agency of man otherwise it would not be conversion but compulsion. This is made clear by the American Standard Version's translation of Matthew 13:15; 18:3; and Acts 3:19. Conversion is shown to be a willing act on man's part by its use of the verb "turn." One chooses as to whether or not he turns. His turning, or failure to turn, is not a predestined act of God.
The understanding of the individual. Unless one understands his sinful condition and the divine remedy of it, he cannot be converted. As already noted, Matthew 13:15 shows an understanding of God's will is a requirement for conversion to take place.
The word of God. Without the word of God, there can be no understanding of God's will. Psalm 19:7 states, "The law of the Lord is perfect, converting the soul." A study of God's word reveals the person's sinful condition and the remedy for it and then gives the necessary understanding so that there will be sufficient incentive for turning. In every case of conversion in the book of Acts, there was gospel preaching. God converts people in the same way He draws them -- through the word (John 6:44–45).
Obedience to the word of God. Mere knowledge of the word and belief in what it teaches are not enough to save. Obedience brings conversion and salvation (Rom. 6:17, 18; Heb. 5:8–9; Matt. 7:21).
The initial change is that of principle or guide in life. When one is truly converted, he will no longer live by the rule of sin but will allow the word of God to guide him. God's word becomes his permanent guide. Hearing the word produces faith which changes the heart and thereby cancels the love of sin. The believer is then moved to repent of his sin and alter his conduct thereby canceling the practice of sin.
There is also a change in relationship. This change is brought about by baptism into Christ. Baptism cancels the guilt of sin and allows one to be in fellowship with God (Rom. 6:3–4; Gal. 3:26–27; Eph. 1:3, 7).
There are consequences of conversion, demands the Lord makes of those who have been converted. The converted need to look to God's word to learn their obligations as converted people and then perform them. The unconverted need to give attention to the word of God to see what they must do to be converted.